Technical Summary of ASTM A350 LF2 Flanges

---

Key Features of ASTM A350 LF2 WNRF Flanges

• Excellent impact toughness at low temperatures
• High resistance to brittle fracture
• Good weldability and fabrication performance
• Suitable for sour gas service (H₂S environments)
• NACE MR0175 / ISO 15156 compliant
• Reliable sealing performance under pressure
• Compatible with cryogenic and LNG piping systems

---

Product Range

We manufacture a full range of ASTM A350 LF2 forged flanges:

• Weld Neck Flange (WNRF)
• Blind Flange
• Slip-On Flange
• Socket Weld Flange
• Threaded Flange
• Lap Joint Flange

Manufacturing Standards

• ASME B16.5
• ASME B16.47 Series A
• ASME B16.47 Series B
• MSS SP-44

---

ASTM A350 LF2 Chemical Composition (%)

---

Carbon Equivalent (CE)

The Carbon Equivalent (CE) formula is used to evaluate weldability and cracking resistance:

$CE=C+\frac{Mn}{6}+\frac{Cr+Mo+V}{5}+\frac{Ni+Cu}{15}$

Lower CE values improve weldability and structural integrity in low-temperature applications.

---

ASTM A350 LF2 Mechanical Properties

The hardness limitation of 197 HB maximum meets the requirements for carbon steel forgings under NACE MR0175 / ISO 15156.

---

Charpy V-Notch Impact Testing

Charpy V-notch impact testing is mandatory for ASTM A350 LF2 flanges to ensure toughness under low-temperature conditions.

Standard Test Temperature

• LF2 Class 1: -46°C (-50°F)
• LF2 Class 2: 0°C (-18°F)

Impact Test Requirements

Testing is conducted in accordance with ASTM A370 or ASTM A1058.

---

ASTM A350 LF2 Heat Treatment

ASTM A350 Grade LF2 flanges are commonly supplied in:

• Normalized condition
• Normalized & Tempered condition
• Quenched & Tempered condition

Heat Treatment Process

Normalizing

• Heating temperature: 860 – 920°C
• Air cooling after soaking

Hardening

• Heating temperature: 890 – 960°C
• Water quenching

Tempering

• Minimum reheating temperature: 590°C
• Air cooling after holding period

Proper heat treatment ensures the optimal balance of strength, toughness, and weldability.

---

Manufacturing Process

Forging Process

• Hot forging temperature: 900 – 1200°C
• Controlled soaking time
• Air cooling after forging
• Dimensional machining according to ASME standards

Inspection & Testing

• PMI Testing
• UT Inspection
• Hardness Testing
• Charpy Impact Testing
• Dimensional Inspection
• Visual Examination

Mill Test Certificates (MTC EN 10204 3.1) are available upon request.

ASTM A350 LF2 NACE MR0175 Compliance

ASTM A350 LF2 flanges can be manufactured to comply with NACE MR0175 / ISO 15156 requirements for sour service environments containing hydrogen sulfide (H₂S).

To meet NACE MR0175 compliance requirements, ASTM A350 LF2 forged flanges must satisfy controlled hardness, chemical composition, heat treatment, and material traceability requirements.

---

ASTM A350 LF2 vs ASTM A105

ASTM A350 LF2 is specifically designed for low-temperature service, while ASTM A105 is primarily used for ambient and elevated temperature piping systems.Want to know more difference about ASTM A350 LF2

Pls click ASTM A350 LF2 vs ASTM A105 

---

Dimensions & Pressure Ratings

Available Sizes

• 1/2″ to 60″
• DN15 to DN1500

Pressure Classes

• Class 150
• Class 300
• Class 600
• Class 900
• Class 1500
• Class 2500

Face Types

• Raised Face (RF)
• Ring Type Joint (RTJ)

---

Applications of ASTM A350 LF2 Flanges

ASTM A350 LF2 flanges are widely used in:

• LNG plants
• Cryogenic piping systems
• Oil & gas pipelines
• Sour gas service (H₂S)
• Petrochemical plants
• Offshore platforms
• Refinery piping systems

They are commonly used together with:

• ASTM A333 Grade 6 pipes
• ASTM A420 WPL6 fittings

---

Dual Certified ASTM A105 / ASTM A350 LF2 Flanges

We also supply dual-certified ASTM A105 / ASTM A350 LF2 flanges.

Dual certification allows the material to satisfy both:

• ASTM A105 for ambient temperature service
• ASTM A350 LF2 for low-temperature applications

This reduces inventory costs and improves material flexibility for piping projects.

FAQ – ASTM A350 LF2 Flanges

What is ASTM A350 LF2 used for?

ASTM A350 LF2 is used for low-temperature piping systems requiring high impact toughness and resistance to brittle fracture.

---

What temperature can ASTM A350 LF2 withstand?

ASTM A350 LF2 is typically suitable for continuous service down to -46°C (-50°F).

---

Is ASTM A350 LF2 suitable for LNG service?

Yes. ASTM A350 LF2 is widely used in LNG and cryogenic piping systems because of its excellent low-temperature toughness.

---

What is the difference between ASTM A350 LF2 and ASTM A105?

ASTM A350 LF2 is designed for low-temperature applications requiring Charpy impact testing, while ASTM A105 is mainly used for ambient and elevated temperature service.

---

Is ASTM A350 LF2 compliant with NACE MR0175?

Yes. ASTM A350 LF2 flanges can meet NACE MR0175 / ISO 15156 requirements for sour gas service.

---

Is ASTM A350 LF2 weldable?

Yes. ASTM A350 LF2 has good weldability and is suitable for welding in low-temperature piping systems.

FlgWN, A350LF2, CL2500, RTJ, 16IN 2.375W, B16, Flange – Weld Neck Carbon Steel Per ASTM A350 Grade LF2 ASME Class  2500 Ring Type Joint 2.375 Inch 

---